/* Copyright (C) 2004 Viktor T. Toth <http://www.vttoth.com/>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.  See the GNU General Public License for more details.
 *
 * Classification of the anti-deSitter metric
 *
 */

if get('ctensor,'version)=false then load(ctensor);
("Computing the Petrov classification of the anti-deSitter metric")$
("We use frames")$
cframe_flag:true;
("We set up the metric by hand")$
ct_coords:[t,x,theta,phi];
(lfg:ident(4),lfg[1,1]:-1,lfg)$
fri:matrix([ 1/sqrt(2), -%i*a*cos(t/a)/sqrt(2),0,0],
           [-%i*1/sqrt(2),a*cos(t/a)/sqrt(2),0,0],
    [0,0,a*cos(t/a)*sinh(x)/sqrt(2), %i*a*cos(t/a)*sin(theta)*sinh(x)/sqrt(2)],
    [0,0,a*cos(t/a)*sinh(x)/sqrt(2),-%i*a*cos(t/a)*sin(theta)*sinh(x)/sqrt(2)]);
cmetric(false);
ug:invert(lg);
weyl(false);
nptetrad(false);
ctrgsimp:true;
psi(true);
("And obtain the Petrov class")$
petrov();

/* End of demo -- comment line needed by MAXIMA to resume demo menu */